<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>选择器</title>
    <style>
        /*id选择器*/
        #d1{
            color:red;
        }
        .c1{color:blue}/*class 选择器*/
        /*分组选择器*/
        h3,#d1,c1{
            background-color:yellow;
        }
        input[type='password']{
            background-color:purple;
        }
    </style>
</head>
<body>
<input type="text">
<input type="password">
<h3>我是h3</h3>

<div id="d1">div1</div>
<div>div2</div>
<div class="c1">div3</div>

<span class="c1">span1</span>
<span>span2</span>
<span>span3</span>


</body>
</html>